---
title: willPopUpNotification
framework: appkit
role: symbol
role_heading: Type Property
path: appkit/nspopupbuttoncell/willpopupnotification
---

# willPopUpNotification

This notification is posted just before a pop-up menu is attached to its window frame.

## Declaration

```swift
class let willPopUpNotification: NSNotification.Name
```

## Discussion

Discussion You can use this notification to lazily construct your part’s menus, thus preventing unnecessary calculations until they are needed. The notification object can be either a pop-up button or its enclosed pop-up button cell. This notification does not contain a userInfo dictionary. To observe this notification using Swift concurrency, use NSPopUpButtonCell.WillPopUpMessage.